Perhaps you should try some spelling variations:
thiet hach » thien hach, thuyet hach, thiet hai
hanh trinh » canh tranh, hanh chinh
hoc thiet » hoc thieu, hoc thuyet, hoc hien
hang cong » dang cong, hang nong, thanh cong
bang cong » dang cong, bang song, dung cong
manh toan » thanh toan, anh tuan, tinh toan
trinh va » trinh van, trinh vat, trinh ve
san toan » van toan, dan toan, xuan toan

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: hoc thiet hach - hanh trinh va ((hang cong) or (bang cong)) ((san toan) or (manh toan)) cao~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc thiet hach - hanh trinh va ((hang cong) OR (bang cong)) ((san toan) OR (manh toan)) cao.
• Adding a wildcard symbol may retrieve word variants: hoc thiet hach - hanh trinh va ((hang cong) or (bang cong)) ((san toan) or (manh toan)) cao*.